1. Field of the Invention
The present invention relates to a gas turbine plant. Especially, the present invention relates to a gas turbine plant with a monitoring unit to monitor temperature in a turbine outlet and to detect an extraordinary state of the gas turbine plant.
2. Description of the Related Art
FIG. 1 shows an example of a conventional gas turbine plant. The gas turbine plant shown in FIG. 7 is comprised of a compressor 101, a gas turbine section 102, a combustion section 103 and a power generator 104. External air is taken in by the compressor 101, and is compressed, and supplied to the combustion section as compression air 105. Fuel 106 is supplied to the combustion section 103. The combustion section 103 combusts the fuel 106 using the compression air 105 to form the combustion air 110. The combustion air 110 is discharged from an exhaust section 112 as exhaust gas 111 after driving the turbine section 102.
N temperature detectors (N is a positive integer) 113 are provided in the exhaust section 112 in the neighborhood of an outlet of the gas turbine section 102. The N temperature detectors 113 are on N positions of the circumference of the exhaust section 112 in a constant interval. The N temperature detectors 113 monitor and measure the temperatures T1 to Tn on N positions in the neighborhood of the turbine outlet of the gas turbine section 102, i.e., blade path temperatures. The measured temperatures T1 to Tn are supplied to a monitoring unit 115. The monitoring unit 115 compares each of the temperatures T1 to Tn and a predetermined target value. The monitoring unit 115 detects an extraordinary state of the gas turbine plant when the difference of each of the temperatures T1 to Tn and a predetermined target value is equal to or larger than a tolerable level and emits a warning signal.
However, the temperatures T1 to Tn in the neighborhood of the turbine outlet change even when the gas turbine plant is operating normally. When the output of the gas turbine plant changes, swirler phenomenon is caused. As a result, the combustion gas 110 outputted from the combustion section 103 passes through the turbine section 102 in a twisted state. When the combustion gas 110 is twisted, the blade path temperatures T1 to Tn change. Such changes of the blade path temperatures T1 to Tn are not caused due to the extraordinary state of the combustion section 103.
Therefore, it is not possible to improve a detection sensitivity of the extraordinary state of the combustion section 103 by decreasing the tolerable level of the difference between each of the temperatures T1 to Tn and the predetermined target value, if the changes of the blade path temperatures T1 to Tn are considered.
In conjunction with the above description, a steam monitoring system in a steam cooled type gas turbine is disclosed in Japanese Laid Open Patent Application (JP-P2000-18050A). In this reference, cooling steam is supplied to a cooling object such as a combusting unit and winds. A temperature detector detects an exit temperature of the cooling steam after the cooling. A control apparatus inputs a detection signal from the temperature detector, and compares the detection signal with a predetermined signal. Also, the control apparatus generates a warning signal, a signal for adjusting an opening degree of a fuel flow rate adjusting valve or closing a closing valve, when the detection signal exceeds a predetermined signal.
Therefore, an object of the present invention is to provide a gas turbine plant which monitors blade path temperatures to detect an extraordinary state of a combustion section more correctly.
Another object of the present invention is to provide a gas turbine plant which has a high detection sensitivity of an extraordinary state of a combustion section, even if the changes of the blade path temperatures are caused.
In an aspect of the present invention, a gas turbine plant includes a combustion section, a turbine section, an exhaust section, a temperature detecting unit, and a monitoring unit. The combustion section combusts fuel using air to generate combustion gas. The turbine section is driven with the combustion gas from the combustion section. The exhaust section is connected to the turbine section to exhaust the combustion gas from the turbine section. The temperature detecting unit is provided in the exhaust section to measure a temperature of the combustion gas. The monitoring unit generates a warning signal based on a tolerable level and data corresponding to a temporal change of the temperature measured by the temperature detecting unit to indicate an extraordinary state of the gas turbine plant.
The monitoring unit may include a temperature change determining section which compares the tolerable level and the data corresponding to the temporal change of the measured temperature and generates the warning signal based on the comparison result. In this case, the temperature change determining section may include a delay unit and a difference calculating unit. The delay unit delays the measured temperature by a predetermined time period to produce a delayed temperature. The difference calculating unit calculates a difference between the delayed temperature and the measured temperature and outputs the calculated difference as the data corresponding to the temporal change of the measured temperature.
Also, when the gas turbine plant include a plurality of the temperature detecting units, the monitoring unit may include an averaging circuit and a plurality of temperature change determining sections. The averaging circuit calculates an average temperature of a plurality of the temperatures measured by the plurality of temperature detecting units. Each of the plurality of temperature change determining sections compares the tolerable level and the data corresponding to the temporal change of a temperature difference between the average temperature and a corresponding one of the plurality of measured temperatures and generates the warning signal based on the comparison result. In this case, the temperature change determining section may include a first difference calculating unit, a delay unit and a second difference calculating unit. The first difference calculating unit calculates the temperature difference between the average temperature and the corresponding measured temperature. The delay unit delays the temperature difference by a predetermined time period to produce a delayed temperature difference. The second difference calculating unit calculates a difference between the delayed temperature difference and the temperature difference and outputs the calculated difference as the data corresponding to the temporal change of the temperature difference.
Also, the tolerable level may be determined based on data varying in correspondence to an output of the gas turbine plant. In this case, when the gas turbine plant may include a plurality of the temperature detecting units, the monitoring unit may include an averaging circuit which calculates an average temperature of a plurality of the temperatures measured by the plurality of temperature detecting units, and the data varying in correspondence to an output of the gas turbine plant is the average temperature. Instead, the data varying in correspondence to an output of the gas turbine plant may be a quantity of the fuel supplied to the combustion unit. Otherwise, when the gas turbine plant may include a fuel control valve, the data varying in correspondence to an output of the gas turbine plant may be an opening degree of the fuel control valve.
Also, the monitoring unit further may include a determining unit which compares the measured temperature and a predetermined threshold level and generates another warning signal based on the comparison result.
Also, when the gas turbine plant includes a plurality of the temperature detecting units, the monitoring unit further may include an averaging circuit which calculates an average temperature of a plurality of the temperatures measured by the plurality of temperature detecting units; and a plurality of determining units, each of which compares a corresponding one of the measured temperatures and the average temperature and generates another warning signal based on the comparison result.
In another aspect of the present invention, a method of operating a gas turbine plant is achieved by (a) combusting fuel using air to generate combustion gas; by (b) driving a turbine with the combustion gas; by (c) exhausting the combustion gas from the turbine; by (d) measuring a temperature of the combustion gas; and by (e) generating a warning signal based on a tolerable level and data corresponding to a temporal change of the temperature measured by the temperature detecting unit to indicate an extraordinary state of the gas turbine plant.
In this case, the (e) generating step may be achieved by (f) comparing the tolerable level and the data corresponding to the temporal change of the measured temperature to generate the warning signal based on the comparison result. In this case, the (f) comparing steps may include delaying the measured temperature by a predetermined time period to produce a delayed temperature; and calculating a difference between the delayed temperature and the measured temperature to output the calculated difference as the data corresponding to the temporal change of the measured temperature.
Also, the (d) measuring step may be achieved by measuring a plurality of the temperatures of the combustion gas at a plurality of positions, and the (e) generating step may be achieved by calculating an average temperature of a plurality of the measured temperatures; and by (g) comparing the tolerable level and the data corresponding to the temporal change of a temperature difference between the average temperature and a corresponding one of the plurality of measured temperatures to generate the warning signals based on the comparison result. In this case, the (g) comparing step may include calculating the temperature difference between the average temperature and the corresponding measured temperature; delaying the temperature difference by a predetermined time period to produce a delayed temperature difference; and calculating a difference between the delayed temperature difference and the temperature difference to output the calculated difference as the data corresponding to the temporal change of the temperature difference.
Also, the tolerable level may be determined variably based on data corresponding to an output of the gas turbine plant.